CN114731079A

CN114731079A - Liquid cooling type motor

Info

Publication number: CN114731079A
Application number: CN202080079237.7A
Authority: CN
Inventors: G·塔迪; D·方蒂
Original assignee: Nedco Logo Citroen Electric Motor Co ltd
Current assignee: Nedco Logo Citroen Electric Motor Co ltd
Priority date: 2019-11-14
Filing date: 2020-11-04
Publication date: 2022-07-08
Also published as: US20220399770A1; FR3103332B1; EP4059122A1; FR3103332A1; WO2021094670A1

Abstract

The present invention relates to a liquid-cooled rotating electrical machine including a permanent magnet type rotor and a wound stator, the rotor including: (i) at least one rotor sheet metal stack, (ii) magnets housed in the sheet metal stack, (iii) front and rear flanges adjacent to the sheet metal stack, the electric machine being configured for ensuring cross-flow of the cooling liquid within the rotor sheet metal stack.

Description

Liquid cooling type motor

Technical Field

The present invention relates to a rotating electrical machine, and more particularly to a rotating electrical machine cooled by the circulation of a liquid, in particular an oil, at least partly circulating along the axis of the machine.

The invention relates more particularly to alternating current synchronous or asynchronous machines. The invention relates in particular to a traction or propulsion machine for Electric (Battery Electric Vehicle) and/or Hybrid (Hybrid Electric Vehicle-Plug-in Hybrid Electric Vehicle) motor vehicles, such as passenger cars, vans, trucks or buses. The invention also applies to rotating electrical machines for industrial and/or energy production, in particular for naval, aeronautical or wind power.

Background

It is known to cool the winding coil heads of the stator by a cooling liquid which is ejected by the rotor onto these winding coil heads during operation of the electrical machine.

Application JP2003324901 describes an electric machine with a rotor of the permanent magnet type, in which the cooling liquid is brought to the rotor through an axial duct centred on the rotation axis and circulated by radial ducts up to other ducts extending axially along the magnets to cool these magnets. The liquid leaves the rotor at the ends of these cooling ducts of the magnet to be sprayed on the winding coil heads of the stator. The rotor has a particular arrangement in which a peripheral crown is coupled to the shaft at its centre.

Application US2010/0194220 describes another liquid-cooled electric machine involving the circulation of a liquid inside the rotor to cool the magnets. This request mentions the risk that in case of sputtering on these winding coil heads the cooling liquid removes insulation (layer) from the winding coil heads. To reduce this risk, the rotor comprises end pieces added to the stack of rotor plates (rotor plate pack), thus forming in combination a channel for the liquid, which channel leads to the outside by an outlet situated radially set back from the radially outward surface of the rotor. Such an arrangement increases the number of constituent parts of the machine and complicates its production. Furthermore, less cooling of the winding coil heads is detrimental to the performance of the machine.

US2019/0068012 discloses a rotor cooled by liquid circulation. This liquid flow is discharged via through openings embodied in the end flange.

Disclosure of Invention

The invention aims to improve the cooling of an electric machine cooled by the circulation of a liquid.

The present invention is directed to satisfying this need and achieves the same by a liquid-cooled rotary electric machine including a magnet-type rotor and a wound stator, the rotor including:

(i) at least one stack of rotor metal sheets,

(ii) a magnet housed in the stack of metal plates,

(iii) front and rear flanges adjacent the sheet metal stack,

the electric machine is configured for ensuring cross-flow of the cooling liquid within the rotor sheet metal stack.

In particular, the liquid can circulate in cooling ducts of the rotor sheet metal stack, which are angularly offset around the axis of revolution, wherein cooling ducts in which the liquid circulates towards the rear preferably alternate with cooling ducts in which the liquid circulates towards the front, which are preferably parallel and associated with the respective poles of the rotor.

Preferably, the electric machine comprises a supply system for supplying the front and rear flanges with cooling liquid, from which front flange the liquid for supplying the front flange flows through the stack of metal sheets to the rear flange by at least one cooling duct before leaving the rotor by at least one discharge duct, which is at least partially delimited by the rear flange, and from which the liquid for supplying the rear flange flows to the front flange by at least one cooling duct of the stack of metal sheets before leaving the rotor by at least one discharge duct, which is at least partially delimited by the front flange.

The discharge duct preferably opens opposite the winding coil heads of the stator in order to enable the sprayed liquid to cool these winding coil heads.

The present invention can cool the motor while limiting the impact force of the cooling fluid against the stator. The manufacture of the motor is still simple and the flange can be implemented simply (as a separate part if desired). The invention enables to obtain a balanced cooling along the longitudinal axis of the machine.

The front flange may be a flange on the side of the shaft of the rotor, which is embodied to mechanically grip the driven element, and this side of the shaft may comprise a drive pinion, which is, for example, machined together with the shaft.

Preferably, the front and rear flanges are each axially embodied against the rotor sheet metal stack at the end. Thus, the aforementioned discharge duct may be concavely formed on the face of the flange turned toward the rotor sheet metal stack. Each flange may comprise at least one supply conduit from which liquid for supplying the flange is conveyed to at least one cooling conduit. The supply duct may be concavely formed on a face of the flange turned toward the rotor-metal-plate stack. The supply conduits may each have a Y-shaped or T-shaped form, or any other suitable form.

Preferably, the front and rear flanges are identical and angularly offset so as to feed different cooling ducts, the cooling duct through which the liquid circulating from said front flange towards said rear flange flows being preferably implemented within the odd poles, and the cooling duct through which the liquid flows in the opposite direction being preferably located within the even poles.

Preferably, the cooling duct is formed by receptacles for receiving the magnets, by the space left free by the magnet or magnets in these receptacles. This free space can be used in particular as a magnetic flux for the pipe (guide) in the metal sheets of the stack.

In a variant, the cooling duct may not be a receptacle for receiving the magnet. The cooling ducts may, for example, be formed in grooves that are used for cooling, or for other purposes, such as for manufacturing processes.

Preferably, the discharge conduit has an outwardly flared form. The discharge duct may be formed by a recess, the depth of which increases as approaching the outer periphery of the flange. Each discharge conduit may have a substantially trapezoidal form. The form of the discharge duct may limit the ejection speed of the liquid while enabling to sprinkle a (larger) area of the winding coil heads of the stator.

Preferably, the supply and discharge conduits alternate in a circumferential direction on each flange.

The supply to the flanges is performed by the shaft of the rotor, which may comprise a central duct and radial ducts on the aforementioned supply ducts to the front and rear flanges. The radial ducts for feeding the forward flanges may be angularly offset with respect to the radial ducts for feeding the aft flanges to account for the angular offset between the flanges.

The electric machine may comprise at least one axial duct for distributing the cooling fluid towards the or a flange, which may be formed in the rotor mass or between the rotor mass and the shaft along the shaft. The axial distribution duct or ducts may pass axially through at least a portion of said rotor mass. These axial distribution ducts may for example be arranged in the stack of metal sheets and extend flush with the shaft.

The flange may be supplied with cooling liquid by an axial duct for distributing said cooling fluid, said axial duct being formed in said rotor mass along said shaft. Preferably, each flange is a cast part and is in particular made of aluminum or an aluminum alloy. The geometry of the flange with the supply or discharge ducts formed at the interface between the flange and the rotor sheet metal stack allows for a very simple manufacture without the need for reworking or drilling. Other materials than aluminum may be used, such as other less magnetic materials.

The object of the present invention is also a cooling method for cooling a rotating electrical machine, the rotor of which comprises a stack of metal plates and magnets housed in the stack of metal plates and which rotates inside a stator having winding coil heads, in particular an electrical machine as described above, wherein the liquid is made to circulate in both directions inside the rotor to cool the magnets and then to be sprayed on the winding coil heads of the stator after passing through the stack of metal plates (11) of the rotor.

The flow through the sheet metal stack, which is carried out between the front and rear flanges, may in particular take place crosswise over the entire length of the sheet metal stack.

The present invention is capable of cooling the stator while limiting the impact force of the cooling fluid against the stator. The enlarged section of the outlet of the discharge conduit avoids the formation of powerful jets directed towards the stator. Preferably, the liquid is circulated axially within the stack and then radially ejected. An elbow formed at the interface between the rotor sheet metal stack and the flange disrupts flow and thus reduces the impact velocity of the liquid impacting the winding coils.

Preferably, the cooling fluid is made to circulate axially inside the rotor sheet metal stack through its grooves, which are implemented in the housing for housing the magnets. It is also preferred that all odd poles are cooled by flow in one direction and all even poles are cooled by flow in the opposite direction.

Drawings

Other objects, features and advantages of the present invention will become more apparent upon reading the following non-limiting description and upon reference to the drawings in which:

figure 1 shows, partially and schematically, a longitudinal section of an electric machine according to the invention,

figure 2 shows the rotor of figure 1 alone and shows the circulation of the cooling fluid in both directions within the rotor sheet metal stack,

the transverse section of figure 3 shows, partially and schematically, a rotor showing the flange in its thickness,

figure 4 shows a detail of the rotor sheet metal stack,

figure 5 shows the flange separately, and

figure 6 shows the cooling of the coil heads by means of the sprayed liquid sprayed on these coil heads by the discharge ducts of the flange.

Detailed Description

Fig. 1 shows, in part, an electric machine 1 according to the invention, comprising a rotor 10 which rotates inside a stator 20 about a rotational axis X.

The stator 20 comprises a stator sheet metal stack 21 (containing the rotor sheet metal inside) provided with notches for the electrical conductors of the windings. These conductors extend axially beyond the sheet metal stack 21 to form a winding coil head 22, also referred to as a bun.

The rotor 10 comprises at least one rotor sheet metal stack 11 carried by a shaft 40 guided by bearings (not shown). The shaft 40 carries at the front a pinion 48 which meshes with a driven element, not shown. The end of the shaft 40 carrying the pinion gear 48 is also referred to as the "drive end".

As can also be seen in fig. 4, the stack 11 comprises receptacles 13 in which are arranged permanent magnets 14, the magnetization of which can be performed, if necessary, after (themselves) they have been mounted in the receptacles 13.

The rotor 10 comprises front and rear two

end flanges

30a and 30b, which are arranged to abut against (two) corresponding ends of the stack 11.

The two

flanges

30a and 30b are identical in the example considered and have, as shown in fig. 5, on their own face 31 turned towards the stack 11, a set of concave bulges and define circulation channels for the circulation of a cooling fluid.

The cooling fluid, which is preferably an oil, is brought about by a central duct 41 of the shaft 40, as shown in fig. 2.

This duct 41 communicates with the front flange 30a by a radial duct 42 and with the rear flange 30b by further radial ducts 43, which open out into openings in the central duct 41, as seen in fig. 2, these ducts 43 being angularly offset with respect to the duct 42.

If reference is made to fig. 5, it can be observed that each

flange

30a or 30b comprises a supply duct 32, having a substantially Y-shaped form, and a discharge duct 33, which alternates with the supply duct 33 and opens onto the outer periphery of said flange.

As can be seen in fig. 3, the feed ducts 32 each have a radial branch 32a aligned with and opening onto a radial duct 42 of the shaft 40, and two inclined branches 32b in which the liquid flux circulating in the branch 32a is distributed.

The branches 32b are at least partially superimposed at the grooves 16 implemented in the metal plates of the stack 11 and form longitudinal cooling ducts 17 through the stack 11, as shown in figures 1 and 6.

The grooves 16 are made by cutting a metal plate with receptacles 13 for receiving the magnets 14 and serve on the magnetic plane for the magnetic flux in the metal plate of the stack 11 for the conduits (guidance). The discharge ducts 33 are superimposed at the pole recesses 16, which are located between the recesses fed by the feed ducts 32.

In the example considered, the rotor has 8 poles and each

flange

30a or 30b comprises four supply ducts 32 and four discharge ducts 33.

The

flanges

30a and 30b are angularly offset by 45 ° in the example considered.

Thus, the ducts 17 formed by the grooves 16 of the odd poles within the stack 11 are superimposed at the ends at the supply duct 32 of the front flange 30a and at the ends at the discharge duct 33 of the rear flange 30b, and the ducts 17 formed by the grooves of the even poles are superimposed at the ends at the discharge duct 33 of the front flange 30a and at the opposite ends at the supply duct 32 of the rear flange 30 b.

This makes it possible to generate a circulation of the cooling liquid in both directions within the rotor.

More precisely, as shown in fig. 2 and 3, the liquid reaching the central duct 41 can be sent by the radial ducts 42 to the front flange 30a and to the supply ducts 32 of the ducts 17 for supplying the odd poles, and circulate inside the stack of metal sheets from the front towards the rear before reaching the discharge ducts 33 of the rear flange 30b (marked circulation 1 on fig. 2 and 3).

The liquid that has not passed through the duct 42 circulates along the central channel 41 to reach the duct 43 and then to the rear flange 30b and the supply duct 32 for supplying the latter. The liquid then circulates in the ducts 17 of even poles from the rear towards the front (marked flow 2 on figures 2 and 3) before reaching the discharge duct 33 of the front flange 30 a.

Each discharge duct 33 has a general form of a substantially trapezoidal shape with opposite lateral edges 36 diverging outwardly, as shown in figure 5. The angular range occupied by the discharge conduit 33 on the periphery of said flange is for example higher than or equal to X30 ° about the axis.

The depth of the discharge conduit 33, that is to say the distance by which the discharge conduit is embodied to recede relative to the plane of the face 31 of the flange, can increase with increasing distance from the center of the flange, as shown in fig. 6.

In fig. 6 it is observed that the bottom 37 of the discharge conduit 33 has a planar form which is inclined away from the stack 11.

The inclination of the outlet of the discharge conduit 33, and of the bottom 37 of this discharge conduit, enables the (larger) section of the winding coil head 22 to be flooded with said cooling liquid, as shown in fig. 6.

The

flanges

30a and 30b are preferably made by casting, and are made of aluminum or an aluminum alloy, and may be held against the stack 11 by a not-shown tie body.

The faces 31 of the

flanges

30a and 30b are advantageously embodied so as to cover the magnets 14 and thus contribute to the axial fixing of (themselves) within the stack 31.

The operation of the motor is as follows.

During rotation of the rotor 10, the cooling liquid circulates in opposite directions inside the stack of metal plates, as described above, and cools the magnets. The liquid exiting from the duct 17 disposed inside the stack 11 is sprayed by the discharge duct 33 on the winding coil head 22 due to centrifugal force.

Due to the enlarged cross section of the outlet of the discharge conduit 33, the formation of fine jets at high pressure, which would be likely to damage them by impact on the winding coil heads, is avoided.

In the example considered, the presence of the bend formed at the interface between the axial cooling duct 17 and the radial discharge duct 33, brakes the liquid and further reduces the impact velocity on the winding coil heads.

The cooling fluid sprayed on the stator may be recovered and pumped to the exterior of the stator to be cooled prior to re-injection by the recessed shaft 40.

Of course, the invention is not limited to the examples just described.

The rotor may be twisted or untwisted.

The rotor may be implemented with other channels for cooling fluid. The angular offset between the flanges may differ from 45 deg. depending on the polarity of the motor.

Typically, this offset may be 360 °/n plus the possible twist angle of the rotor, where n represents the number of poles of the rotor. The offset may be, for example, 60 ° for a 6 pole machine.

Preferably, all the poles are cooled, but in a variant only some of the poles, for example every second or every fourth pole, are cooled.

The flange may have a form different from that shown.

Claims

1. A liquid-cooled rotating electrical machine (1) comprising a magnet (14) type rotor (10) and a wound stator (20), the rotor comprising:

(i) at least one rotor sheet metal stack (11),

(ii) a magnet (14) housed in the stack of metal plates,

(iii) a front (30a) and a rear (30b) flange adjacent to the stack of metal sheets (11),

the electric machine being configured for ensuring cross-flow of the cooling liquid within the rotor sheet metal stack, the electric machine comprising a supply system for supplying the front and rear flanges with cooling liquid,

liquid for supplying the front flange (30a) flows from the front flange through the stack of metal sheets (11) to the rear flange (30b) by at least one cooling duct (17) before exiting the rotor by at least one discharge duct (33) which is at least partially delimited by the rear flange (30b) and which is intended for supplying the liquid to the rear flange (30b)

Liquid for supplying the rear flange (30b) flows from the rear flange to the front flange (30a) by at least one cooling duct (17) before leaving the rotor by at least one discharge duct (33) delimited at least partially by the front flange (30a),

front and rear flanges are each embodied axially at an end against the rotor sheet metal stack (11), and the discharge duct (33) is concavely formed on a face (31) of the flange turned towards the rotor sheet metal stack.

2. A liquid-cooled rotating electrical machine (1) comprising a magnet (14) type rotor (10) and a wound stator (20), the rotor comprising:

(i) at least one rotor sheet metal stack (11),

(ii) a magnet (14) housed in the stack of metal plates,

the electric machine being configured for ensuring cross-flow of the cooling liquid within the rotor sheet metal stack, the electric machine comprising a supply system for supplying front and rear flanges with cooling liquid,

the liquid for supplying the front flange (30a) flows from the front flange through the stack of sheet metal (11) to the rear flange (30b) by at least one cooling duct (17) before leaving the rotor by at least one discharge duct (33) which is delimited at least partially by the rear flange (30b) and which is delimited at least in part by the rear flange (30b)

each flange (30 a; 30b) is a cast part, in particular made of aluminum or an aluminum alloy.

3. A liquid-cooled rotating electrical machine (1) comprising a magnet (14) type rotor (10) and a wound stator (20), the rotor comprising:

(i) at least one rotor sheet metal stack (11),

(ii) a magnet (14) housed in the stack of metal plates,

the supply to the flanges is performed by the shaft of the rotor, which comprises a central duct (41), said central duct (41) communicating with the front flange (30a) by a radial duct (42) and with the rear flange (30b) by a further radial duct (43).

4. A liquid-cooled rotating electrical machine (1) comprising a magnet (14) type rotor (10) and a wound stator (20), the rotor comprising:

(i) at least one rotor sheet metal stack (11),

(ii) a magnet (14) housed in the stack of metal plates,

the flange is supplied with cooling liquid by an axial duct for distributing said cooling fluid, said axial duct being formed in said rotor mass along said shaft.

5. The electric machine of any of claims 1 to 4, except for claim 3, each flange comprising at least one supply duct (32) from which liquid for supplying the flange is conveyed to at least one cooling duct (17).

6. The electric machine according to claim 5, the supply duct (32) being concavely formed on the face of the flange turned towards the rotor sheet metal stack (11).

7. The electric machine according to claim 5 or claim 6, the supply ducts (32) each having a Y-shaped or T-shaped form.

8. The machine according to any of claims 1 to 7, the front (30a) and rear (30b) flanges being identical and angularly offset so as to feed different cooling ducts (17), the cooling ducts (17) flowed through by the liquid circulating from the front flange towards the rear flange being preferably implemented within odd poles, and the cooling ducts flowed through by the liquid circulating in the opposite direction being preferably located within even poles.

9. The electric machine according to any of claims 1 to 8, the cooling duct being formed by receptacles (13) for receiving the magnets (14), by free spaces (16) left in these receptacles by the magnet or magnets.

10. The electric machine according to any of claims 1 to 9, the discharge duct (33) being formed by a recess, the depth of the recess increasing as approaching the outer periphery of the flange.

11. The electric machine according to any of claims 1 to 10, the supply (32) and discharge (33) ducts alternating in a circumferential direction on each flange (30 a; 30 b).

12. The electric machine according to claim 11, each discharge duct (33) having a substantially trapezoidal form.

13. The electrical machine according to any of claims 1-12, except claim 4, the supply to the flange being performed by a shaft (40) of the rotor.

14. The electrical machine according to any of claims 1-13, the discharge duct (33) opening out opposite a winding coil head (22) of the stator.

15. The electrical machine of any of claims 1 to 14, except for claim 2, each flange (30 a; 30b) being a cast part, in particular made of aluminum or an aluminum alloy.

16. A cooling method for cooling a rotating electric machine according to any one of claims 1 to 15, wherein the liquid is circulated in both directions within the rotor to cool the magnet, and then the liquid is sprayed on the winding coil head of the stator after passing through the metal plate stack (11) of the rotor.